Ive havent been messing around with my ecu too much lately and figured I'd get into it and check some things out. I have an open element K&N filter with the stock intake. I havent flashed my car in the last 4-5k miles. So I figured Id do some logging and see what my fuel trims looked like. I hooked it up in the driveway and revved it up a little. I was expecting my fuel trims to be all over the place. They are all at 100 in evoscan. I cant beleive it. Should I? The car was at normal operating temp.

Also, back when I was doing some tuning last fall, I kept noticing that my 2 byte load values would consistantly be about 20 points higher than the corresponding timing cell that matched the logged timing/rpm. I was thinking that the filter was screwing with the maf readings, therefore messing up the 2 byte load calculation. This is why I started today with looking at airflow and fuel trims. I am seeing 31.45 in Evoscan at idle. Is that normal? Isnt idle where the open filter will mess with things?

 

i could see where the filter may throw the maf off a little but the 31.xx does sound fairly normal for idle

 

31.xx is normal at idle

 

Thanks for the responses. I just downloaded and installed Evoscan 2.1 and also got 2 byte airflow, rpm, and load working. I wasnt logging STFT before. And it definitely has some swings in it (60-105). The 2 byte airflow im seeing now is consistently 2-3 units higher than normal airflow. And normal is now 37-42. Suggestions?

edit: the tutorial Im reading for scaling maf references mitsulogger fuel trims. How would I apply this for Evoscan? My guy says that if stft = 80, that 20% needs to be taken away, instead of added as the tutorial discusses for +10%. So if my Im seeing stft=80 at 40hz, then I need to take my cell of 175 +140 (adder)=215*.2=43 175-43=102. Do got this right? It seems that value would be pretty low, looking at others maf tables.

And I have searched, but how does one go about scaling the open loop section? Or is it not needed if the afr is good?

 

I searched around and found a post by l2r99gst about rescaling Evoscan, so I did that. And now stft goes from -3% to -10% and my airflow readings are steadily in the 41-43 range at idle.

 

It sounds like everyhing is OK in your case. Now that you have your fuel trim formulas correct in EvoScan, now you can see what percentage of fuel the ECU is taking out of adding in to maintain stoich.

Your long term trims should not all be at 0, though, especially with your STFT ranging from -3 to -10. That should eventually make your long term trim around -6 or so and your stft will bounce around 0. If that turns out to be true, then you're fine and you have nothing to worry about.


Eric

 

Thanks again. You guys are great around here. I did a few logs yesterday. My LTFTs all stay at .1008, with STFT ranging the same as before (~0 to -10). I was comparing my maf scaling table to what I think is stock, and mine is not. The lower values are stock, but 100 all the way to 1600 have been increased slightly. This is from an email flash that I got a year ago. I had huge issues with that tune (15-17* timing up top and 9.xxx AFRs).

I am noticing a small dip in airflow that starts at 3500-3800 rpm and affects up to 4500 rpm, is this normal? This also happens just after a load spike of 283 (highest logged) that settles to 267 and goes back up to 270. I cant log boost yet. But didnt notice any major changes on the boost gauge. It hits 21-22 and settles to about 19 at redline. I am attaching a log file. Rename this file to .csv.